QRPGuys Power/SWR Meter w/ internal Dummy Load – $40
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Steve Weber (KD1JV) has designed a combination power meter/SWR bridge with a switchable internal dummy load. It is a nice addition to any QRP station for general use, tweaking transmitters, and testing antennas. It uses the Texas Instrument MSP430G2152 MCU powered with an ordinary 3V Lithium coin cell battery. It has low insertion loss through the binocular transformer and can stay in the circuit continuously or just for adjustments. The digital display is a three digit, 7 segment, led display for SWR and power readings. The useful frequency is 160m-10m. It will show power from 200mW to 10W, with >95% accuracy across all the bands, SWR from 1:1 to ~15:1, and the 50Ω dummy load is good for 12W. I/O connections at the rear are female BNC. Battery life is good (+10hr. at continuous use) and there is a display sleep mode, and a momentary switch for a “quick check” to extend battery life to many times beyond that. The board measures 3.18″ (89mm) x 3.00″ (76mm). All components are through hole. The normal tools required are a soldering iron with a small tip, rosin core solder, and small side cutters. The device can be built in an hour or so. On a difficulty scale of 1 to 5, 5 being the most difficult, this is rated at a 2 to 3 depending on your experience.
Click here for the assembly manual.
Mark (AJ6CU) has come up with a 3D printed case, https://www.thingiverse.com/thing:5333701